The present invention relates to an electrothermic non-impact recording method and apparatus employing an electroconductive ink ribbon containing or coated with a thermal-transferable ink material which is transferred to a receiving surface, for instance, a sheet of paper, upon being heated above a predetermined temperature.
Conventionally there has been proposed an electrothermic non-impact recording method and apparatus in which a recording electrode having a plurality of recording styli arranged in one or more rows, and a return electrode, are brought into contact with an ink ribbon of the above-mentioned type, which ink ribbon is superimposed on a receiving surface. An image-delineating electric current is caused to flow through the ink ribbon, and a thermal-transferable material softened in an image pattern by Joule's heat generated in the ink ribbon immediately below the recording styli, is transferred to the receiving surface.
In this recording method and apparatus, it can occur that an image-delineating signal voltage is applied to a plurality of the recording styli at the same time. Therefore, if portions of the ink ribbon immediately below some of the recording styli happen to be smaller in surface resistivity than are other portions of the ink ribbon, more electric current flows through the portions of the ink ribbon with the smaller surface resistivity than through the other portions thereof. The result is that image dots formed on the ink ribbon are non-uniform in density, or so-called "halos" are produced.